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Date Posted: 18:07:44 02/07/03 Fri
Author: Michel
Subject: Re: Turning off colors on scanned images
In reply to: chris 's message, "Turning off colors on scanned images" on 12:26:52 02/06/03 Thu

Hi Chris,

You can access the individual pixels using the TDibGraphic.RGB property, or ScanLine may be faster but you will need to do more work to separate the channels. So first, set the Red component to 0.

The use the TImageFormatTransform to convert to black and white. Make sure you don't use interpolation for faster results.

Best regards,


>High speed document scanners usually work with
>1 bit images (black/white). They may be equipped
>with red, green or blue lamps to process documents
>that are printed on red, green or blue paper.
>Background of those colors are simply recognised as
>white. <br>
>Another possibility consists of scanning the
>documents with a color scanner and eliminating
>the, say, red channel to suppress anything that
>is red on the document. Before recognising objects
>on such images, e.g. OCR test or bar codes, these
>images have to be converted to 1 bit.<br>
>How do i achieve this the fastes way, i.e.
>suppress one of the color channels and convert
>the image to black and white?

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